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#!/usr/bin/perl
# Process a PuTTY SSH packet log that has gone through inappropriate
# line wrapping, and try to make it legible again.
#
# Motivation: people often include PuTTY packet logs in email
# messages, and if they're not careful, the sending MUA 'helpfully'
# wraps the lines at 72 characters, corrupting all the hex dumps into
# total unreadability.
#
# But as long as it's only the ASCII part of the dump at the end of
# the line that gets wrapped, and the hex part is untouched, this is a
# mechanically recoverable kind of corruption, because the ASCII is
# redundant and can be reconstructed from the hex. Better still, you
# can spot lines in which this has happened (because the ASCII at the
# end of the line is a truncated version of what we think it should
# say), and use that as a cue to remove the following line.
use strict;
use warnings;
while (<<>>) {
if (/^ ([0-9a-f]{8}) ((?:[0-9a-f]{2} ){0,15}(?:[0-9a-f]{2}))/) {
my $addr = $1;
my $hex = $2;
my $ascii = "";
for (my $i = 0; $i < length($2); $i += 3) {
my $byte = hex(substr($hex, $i, 2));
my $char = ($byte >= 32 && $byte < 127 ? chr($byte) : ".");
$ascii .= $char;
}
$hex = substr($hex . (" " x 48), 0, 47);
my $old_line = $_;
chomp($old_line);
my $new_line = " $addr $hex $ascii";
if ($old_line ne $new_line and
$old_line eq substr($new_line, 0, length($old_line))) {
print "$new_line\n";
<<>>; # eat the subsequent wrapped line
next;
}
}
print $_;
}
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